Some thoughts on characteristics of floats in network planning

Network is to design plans by means of network analysis, which is an effective method developed to make schedule plans for large scale projects in the end of 1950s. CPM is one of the main contents in network, and float is the main part. There are nine basic concepts, including total float, front single float, back single float, front common float, back common float, front single back common float, front common back single float, double common float and double single float. The correlation among them can reflect the characteristic of floats and the relationship between activity and total duration or activity and activity and so on. From a new point of view, the paper studied correlation among nine floats on the basis of their concepts, proposed several thought-provoking issues aiming at characteristics of floats, and summed some theorems and deductions.